A marijuana grow operation (pictured) was searched on June 23, 2015 as part of a multi-agency sweep serving marijuana search warrants in Humboldt County’s corner of the remote Island Mountain area. (Lt. Wayne Hanson, provided by Humboldt County Sheriff’s Office)

EUREKA, Calif. — The final totals of assets seized and warrants served during “Operation Emerald Tri-County” — this past week’s marijuana search warrant sweeps in the remote Island Mountain area — were released during a Friday afternoon press conference in Ukiah featuring the three sheriffs of the Emerald Triangle.

In total, deputies from Humboldt, Mendocino and Trinity counties served 20 search warrants, made four arrests and seized or eradicated 86,578 adult marijuana plants, as well as 25 guns and $8,877 in cash. In Humboldt County alone, deputies seized or eradicated an estimated $26.5 million worth of marijuana, according to a Humboldt County Sheriff’s Office press release.

According to the release, deputies served a warrant on a parcel of property in the Island Mountain area where a woman growing approximately 50 marijuana plants was found to be in compliance with state medical marijuana guidelines. No marijuana was seized from her property and she was not arrested.

Seven other warrants at seven other properties served by Humboldt County deputies netted evidence of illegal dumping of garbage, unpermitted grading of land and water diversion, according to the release. No arrests were made in Humboldt County but criminal charges may be filed by the Humboldt County District Attorney’s Office against a suspect or suspects at a later date.

Mendocino County Sheriff Tom Allman said the California Department of Fish and Wildlife played a key role in the operation.

“If Fish and Wildlife had not partnered with us at the very beginning, and had understood the environmental damage that all three counties were suffering from I don’t know if we would have followed through with everything here,” Allman said.

California Department of Fish and Wildlife Lt. Chris Stoots spoke at the conference of his department’s role in the operation.

The primary focus of Fish and Wildlife was to investigate resource violations, this includes streambed alterations, diversion of waterways, tapping of springs, as well as unlawful ponds, damns and reservoirs, Stoots said.

“I’ll say, from the three days I was out there we saw an abundance of that activity,” Stoots said.

In total 97 environmental violations were found during the raid.

“I saw areas that were some of the most devastated areas I’ve ever seen,” Stoots said.

According to Allman, the plants eradicated required well over 50,000 gallons of water a day, and Stoots said the Eel River — below this last week’s sweeps — is running slow, low, warm and full of algae.

Previous reporting below:

Deputies have destroyed around 15,300 marijuana plants this week while serving four search warrants on large grow operations in Humboldt County’s corner of the remote Island Mountain region, according to sheriff’s office officials. No arrests were made.

Day Two of the multi-agency operation began at 6 a.m. Tuesday with sheriff’s office deputies from Humboldt, Mendocino and Trinity counties serving warrants in their respective jurisdictions. This operation is in response to the large-scale marijuana growing operations in the area that may be diverting water, stealing water or grading land without a permit, Humboldt County Sheriff’s Office Lt. Wayne Hanson said.

“The Island Mountain search warrants were served because of the magnitude of the operations,” Hanson said.

California Department of Fish and Wildlife officials are participating in the operation to oversee the effects on watersheds, but have not been involved with the search warrants on the Humboldt County side, where some environmental issues have been seen by officials, Humboldt County Sheriff’s Office Lt. George Cavinta said.

According to California Department of Fish and Wildlife Lt. Chris Stoots, officials have seen “significant” evidence of environmental damage resulting from grows searched during the operation.

“What we’ve seen are several reservoirs … that deal with mountain stream and springs being diverted into ponds and used for unlawful cultivation,” Stoots said.

Figures for plants seized, warrants served and arrests made in Mendocino and Trinity counties were unavailable. Mendocino County Sheriff’s Office Capt. Gregory Van Patten said more information will be released by his office on Friday during a press conference.

Although the current operation is expected to last until Friday, Hanson said the Humboldt County Sheriff’s Office will participate in similar operations during the next four months.

He said that while the Humboldt County Sheriff’s Office receives funding from the federal government for marijuana eradication, no special monies were earmarked for this sweep.

“Whether we had federal funding or not, the marijuana search warrants would still be served,” he said.

The tactics of growers have changed over the past 15 years, with each change causing more environmental damage, Hanson said. After the first sweeps of this kind targeted small growers that cultivated small numbers of marijuana plants outdoors hidden under tree canopies, growers switched to growing indoors using diesel generators for power, leading to diesel spills and oil dumping.

After these types of grow operations were targeted in yearly summer raids, Hanson said growers switched to greenhouses. Greenhouse growers use massive amounts of fertilizers, which leak into the watershed, causing algae blooms.

“The greenhouse effect every year seems to triple in size,” he said. “It’s just evolution of the way to grow marijuana.”

Hanson said growers in the area have an early warning system, with people calling those up the road when official vehicles are seen, allowing growers to leave the premises before police arrive.

“That’s been happening for years … . It looks like I-5 during rush hour,” he said, referring to back-county roads packed with fleeing vehicles prior to law enforcement’s arrival. “We don’t need to have anybody around to prove who lives there.”

The curious can see some suspected grow operations for themselves by looking at dwellings along Hogtrap or Island Mountain roads using Google Earth. Suspected grow operations can be spotted from telltale signs such as water reservoirs, rows of outdoor potted plants or greenhouse-like structures, Hanson said.